i dont think servo has anything to do with it- i think the idea is that making the steering less responsive means that the wheels are going to do less on the road, which i guess increases fuel efficiency and tire wear. this is likley done by altering the power steering response-

ultimately this leads to the drivers potentially incorrect steering movements, and ignoring them if they are not persistent. of course, this will all happen very quickly.

you can test it by sticking it in eco pro, driving off and quickly moving the steering wheel slightly to the left and right- in eco pro you should notice that the car ignores quite alot of the movement you're requesting.

stick it into sport, and repeat, you should notice that it responds to your every move.

the idea isnt to change the steering arc based on driving speeds- its to ignore unintended movement in the wheels....

But the steering wheel is directly connected to the front wheels by rack and pinion, unless you have adaptive steering. The car can only change the amount of electrical power assist. In my F20, the steering response is identical in Eco Pro and Sport. I can't notice any difference in steering effort, so if there is a difference, it must be rather small.

I think you must have the option s0216 servotronic (electric power steering) for this change in management is electrically operated between the different programs eco, comfort and sport. But I like most hydraulic steering, feel the road surface much better. It is therefore all the M cars have hydraulic power steering.

The best advice I got about my BMW
Always drive it in sport mode unless you have your ganny in the car

eco pro is great for saving fuel- its become like a game trying to get the MPG up. even though you can get the same MPGs out of it in sport, the psychological barrier has been broken and i'm more foot heavy.

I checked the specs for my Norwegian 116i M Sport. It has neither servotronic nor active steering. That is why it works perfectly in all driving modes!

The active steering has a unit that works a bit like a differential that can add or subtract steering angle with an electric motor. It can make the steering quicker at low speeds and slower at high speed. It can also make corrections if a slide gets out of hand. I personally don't like interventions like that. It is better to let the driver be in control of the car.

I don't know how the default steering and servotronic are implemented. I have the impression that both are direct rack and pinion setups with electrical power assist on the steering shaft. Maybe one is "stupid", and the other one is "clever", trying to adapt the amount of assist depending on drive modes and speed.

Correction: The electric power assist is not on the steering shaft, but on the steering rack itself. I see no difference in the ETK regarding servotronic or not, so I guess that is only a software option.

The active steering has a unit that works a bit like a differential that can add or subtract steering angle with an electric motor. It can make the steering quicker at low speeds and slower at high speed. It can also make corrections if a slide gets out of hand. I personally don't like interventions like that. It is better to let the driver be in control of the car.

The F20 uses Variable Sport Steering, not the older but complex Active Steering. It reduces the number of steering wheel rotations required to make sharp turns. It is a much simpler mechanical system, steering ratios are adjusted using a variable steering rack.

So not influenced by 'interventions', it is simply a different ratio along the rack, but still a repeatable mechanical link.

But I guess all steering racks have slower gearing around the center position than the ends. I even had that on my E30. Do you have some link or drawing to show how it works on the F20 with the variable ratio?

But I guess all steering racks have slower gearing around the center position than the ends. I even had that on my E30. Do you have some link or drawing to show how it works on the F20 with the variable ratio?

BMW themselves are very reserved about releasing detail, other than brief descriptions and their brochure blurb.

What I have read doesn't seem to show anything more involved than a basic variable rack, obviously the software can enhance the working parameters.

ZF material (like the link) just spell out the basics, page 7 shows the gear profiles, how it physically makes a variable rack, and a little explanation. But we certainly are not into new technology, just an enhanced application instead of a fixed rack system.

I've just been out for a bit of driving, and I can now tell that the Servotronic option feels great! Yesterday, when I drove in the city, and during parking, I left it in Comfort mode. The steering wheel was so light and easy to turn, I could do it with my little finger. Today, I switched over to Sport mode right before going into a corner and onto the motorway, and it was like a different car to drive - like Jekyll and Hyde! The throttle response was great (it's very "dull" in comfort, and even worse in eco pro - but works fine in the city), and the steering wheel tightened up real good! I don't know if it was just in my imagination, but it felt like I got more feedback through te steering wheel.

For info: I have just driven the car about 450 km yet (got it a week ago), so I didn't drive the shit out it.

Itīs actually more than just throttle response. Some people have measured the 118i on a dyno and said there is about a 5hp difference in output between sport+ and comfort modes.
I would assume that the difference towards eco pro would be even more pronounced!

Itīs actually more than just throttle response. Some people have measured the 118i on a dyno and said there is about a 5hp difference in output between sport+ and comfort modes.
I would assume that the difference towards eco pro would be even more pronounced!

How do you manage to run the car on the dyno in Sport+ mode? All four wheels on a rolling road? My car did not cooperate in Sport+ with the two rear hubs connected to Dynapacks. I guess it was confused about the stationary front wheels. Had to select DSC Off, which gave me Comfort engine mapping.